Combination proportional and priority flow divider



L. H. REIMER June 6, 1967 COMBINATION PROPORTIONAL AND PRIORITY FLOW DIVIDER Filed Nov. 1964 AT TGQIFEY LEONARD H. REIMER INVENTOR.

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United States Patent 3,323,533 COMBINATION PROPORTIONAL AND PRIORITY FLOW DIVIDER Leonard H. Reilner, Hutchinson, Kans., assignor to The Cessna Aircraft Company, Wichita, Kans., a corporation of Kansas Filed Nov. 9, 1964, Ser. No. 410,029 3 Claims. (Cl. 137-400) ABSTRACT OF THE DISCLOSURE A pressure responsive device for delivering predetermined proportionate volume flows of fluid from a single pressure fluid supply conduit to two hydraulic circuits of different capacity when the fluid demand from both circuits is low, and for providing a priority large volume flow to the higher capacity circuit when its demand is high, while assuring continuous adequate volume fluid delivery to the lower capacity circuit to assure its proper operation on demand.

This invention relates to a type of hydrodynamically operated valve known as a flow divider, the function of which is to receive fluid under pressure from a Single conduit and to divide and regulate the flow of that fluid from the valve into two separate hydraulic circuits, each of which may serve to actuate hydraulic motors or other hydraulic devices.

7 Some hydraulic systems include a low capacity relatively low pressure circuit, such as a steering circuit, for instance, and also include a large capacity higher pressure circuit. In such systems it is common for the sake of saving power, to keep both circuits continuously charged for instantaneous actuation of their connected hydraulic devices, by means of a low volume source of pressure fluid, and to automatically cut in a large volume source of pressure fluid when the larger capacity circuit, orboth circuits, are in use.

With a conventional flow divider in such a system, the volume of fluid required to satisfy the larger capacity circuit may result in starvation or choking off of the smaller capacity circuit.

It is a primary object of this invention to solve the above described problem by providing a flow divider which functions as a proportional flow divider while it is receiving low gallonage from the pressure fluid source, and which functions as a priority flow divider while it is receiving high gallonage from the source. It thus is capable of providing ample fluid to meet the larger volume requirements of the larger capacity circuit, when it is in use, without starving the low capacity circuit.

The invention, together with other objects will be more clearly understood when the following description is read in connection with the accompanying drawing, in which the single drawing figure is a central longitudinal sectional view through a valve embodying my invention.

Referring to the drawing, the valve illustrated includes a body 10 having an inlet 11, an outlet 12 for a relatively high capacity hydraulic circuit, and an outlet 13 for a relatively low capacity circuit.

Body 10 defines a header or flow distribution chamber 14 in communication with inlet 11, and a valve spool bore 15 in communication with outlets 12 and 13, through ports 27 and 28, the bore being closed at both ends.

A floating valve spool 16 is freely reciprocable in bore 15 and, together with the closed ends of the bore, defines pressure chambers 17 and 18. Spool 16 is provided with an annular groove 19 intermediate its ends, which in the normal position of the spool, as shown, communicates with one of the outlets 13. It is also provided with a fluid 3,323,533 Patented June 6, 1967 metering duct 20 which aflords restricted communication between groove 19 and pressure chamber 18, to slowly equalize pressures in the two spaces.

Body 10 is provided with three flow limiting orifices or ports 22, 23 and 24. All three afford flow from distribution chamber 14 through bore 15 and out through outlets I2 and 13. Port 22 includes a valve seat on which a check valve 25 is normally held seated by a spring 26.

Operation-40W gallonage When only a low gallonage flow is being delivered from the source into inlet 11, and assuming that the flow areas of ports 23 and 24 are the same, and neither of the hydraulic circuits connected to outlets 12 and 13 are in use, the pressure drop created by fluid flowing through ports 23 and 24 will be the same, and the fluid pressure in chambers 17 and 18 will be the same. There will consequently be no pressure differential to move spool 16 in either direction from its normal position, and flow outward through outlets 12 and 13 will be at the same rate.

In case the flow area of port 23 is not equal to the flow area of port 24, the pressure drop across the two ports will likewise be unequal, which will cause unequal pressures in chambers 17 and 18, resulting in movement of the spool in the direction of the chamber 17 or 18, with least pressure. The changed spool position will thus reduce the flow area through opening 27 or opening 28 until the pressures in chambers 17 and 18 have equalized. The volume flow outward through outlets 12. and 13 will then be in direct proportion to the flow areas through the respective ports 23 and 24. It will thus be understood that the relative volume flow of fluid out of each of the outlets 12 and 13 can be predetermined and regulated by the proper relative sizing of ports 23 and 24. I This is true even in the case of internal pressure changes due to the operation of one or the other of the hydraulic circuits connected to outlets 12 and 13. For instance, assuming that ports 23 and 24 are of equal size, if a hydraulic device connected to outlet 12 is actuated, a resistance to flow is created in chamber 17 and the pressure therein rises above the pressure in chamber 18. Spool 16 is forced to move toward the chamber of least pressure (to the right in the drawing) and reduces the flow area through outlet opening 28 (simultaneously enlarging the flow area of opening 27), until the pressure in the two chambers is again equalized, and flow to both circuits through outlets 12 and 13 is equalized.

Operation-Jrigh gall0nage-pri0rity delivery With high gallonage delivery from the source through inlet 11, the valve will operate as described above until the flow of fluid through port 23, due to operation of the high volume hydraulic circuit connected to outlet 12, causes a pressure differential between chambers 14 and 17 which is suflicient to overcome the compression resistance of spring 26, and to move check valve 25 off its seat. This permits a considerable volume of fluid (which had previously been flowing through port 23 and causing the pressure differential) to bypass port 23 to reach chamber 17 and to fiow out through outlet 12. Thus the valve has established a priority volume flow of fluid through outlet 12 to meet the requirements of the connected higher capacity circuit.

However, the fluid flow through outlet 13 will not be choked off, because if the flow through opening 27 becomes too great metering will occur at that opening. This will cause a rise in pressure in chamber 17, which will move spool 16 to the right, reducing the flow area through opening 28. As this opening is reduced in area, the pressure in groove 19 and chamber 18 will also rise until it is equal to the pressure in chamber 17 and spool movement ceases.

To those familiar with this art it will be understood that metering duct 20, by minutely restricting fluid flow between groove 19 and chamber 18, serves to slow the speed of travel of spool 16 in both directions, as well as to closely limit over travel of the spool in either direction. It will also be understood that a spring 26 having any desired compression strength may be used to bypass any desired volume flow of oil around port 23.

From the above it will be seen that my invention provides a flow divider which proportionately regulates the flow of fluid from a single source to two hydraulic circuits when total volume flow is relatively low, and which provides a priority volume flow of fluid to the larger capacity circuit to meet its requirements when total volume flow from the source is relatively large.

Having described the invention with sumcicnt clarity to enable those familiar with this art to construct and use it, I claim:

1. A fluid flow dividing valve comprising:

a valve body having an inlet and two outlets;

means in the body defining two separate open flow paths between the inlet and the respective outlets",

a floating valve spool in the valve body which mete-rs flow through both outlets and is responsive to disproportionate volume flow of fluid through the two outlets to proportionately regulate such flow;

a third and independent fluid flow path defined by said body, affording communication between said inlet and one of said outlets;

and a normally closed check valve controlling fluid flow through said third flow path, and o penable in response to excessive fluid flow through said one outlet to supplement the flow therethrough and afford a continued disproportionate flow through said one outlet as compared to flow through the other outlet.

2. A fluid flow dividing valve comprising:

a valve body having an inlet and two outlets;

a flow distribution chamber in said housing in com munication with said inlet;

a closed-ended valve spool bore in said housing in communication with said outlets;

a floating valve spool in said bore defining therewith a pressure chamber at each end thereof, said spool having an annular groove intermediate its ends which normally communicates with one of said outlets;

a duct in said spool affording communication between the groove therein and a pressure chamber at one end of the spool;

three internal flow restricting ports in the valve body affording communication at spaced points between said flow distribution chamber and said spool bore, one port located to afford flow from the distribution chamber through the spool groove through one of said outlets, and the second and third ports located to afford flow from the distribution chamber into the pressure chamber at the other end of said spool and out through the other of said outlets;

and a spring biased pressure opened check valve normally closing one of the two last mentioned ports.

3. A hydrodynamically actuated valve for variably proportioning fluid flow from a single source to two hydraulic circuits having different volume requirements, comprising:

a valve body having (a) an inlet (b) a valve spool bore with closed ends (c) a fluid distribution chamber in communication with the inlet and in communication with said bore at three longitudinally spaced points along the bore, and

((1) two outlets in communication with said bore at spaced points;

a valve spool reciprocable in said bore and responsive to a difference in the pressure at one outlet port and pressure at the other outlet port to proportion the volume flow of fluid outward through said outlets;

and a spring biased check valve normally preventing free flow of fluid from said distribution chamber through one of said points of communication into said bore, and openable in response to a sufficient pressure diflerential to afford such flow to augment the fluid flowing through one of the other two points of communication.

References Cited UNITED STATES PATENTS 2,462,983 3/1949 MacDuff 137-10l 2,665,704 1/1954 Kanuch l371l0 WILLIAM F. ODEA, Primary Examiner.

H. M. COHN, Assistant Examiner. 

1. A FLUID FLOW DRIVING VALVE VOMPRISING: A VALVE BODY HAVING AN INLET AND TWO OUTLETS; MEANS IN THE BODY DEFINING TWO SEPARATE OPEN FLOW PATHS BETWEEN THE INLET AND THE RESPECTIVE OUTLETS; A FLOATING VALVE SPOOL IN THE VALVE BODY WHICH METERS FLOW THROUGH BOTH OUTLETS AND IS RESPONSIVE TO DISPROPORTIONATE VOLUME FLOW OF FLUID THROUGH THE TWO OUTLETS TO PROPORTIONATELY REGULATE SUCH FLOW; A THIRD AND INDEPENDENT FLUID FLOW PATH DEFINED BY SAID BODY, AFFORDING COMMUNICATION BETWEEN SAID INLET AND ONE OF SAID OUTLETS; AND A NORMALLY CLOSED CHECK VALVE CONTROLLING FLUID FLOW THROUGH SAID THIRD FLOW PATH, AND OPENABLE IN RESPONSE TO EXCESSIVE FLUID FLOW THROUGH SAID ONE OUTLET TO SUPPLEMENT THE FLOW THERETHROUGH AND AFFORD A CONTINUED DISPROPORTIONATE FLOW THROUGH SAID ONE OUTLET AS COMPARED TO FLOW THROUGH THE OTHER OUTLET. 